Recent content by FilterGuy

Patience Grasshopper. Patience.

As long as the Power Supply is correctly set to the target voltage, there should be no reason to worry about over-charging the cells. At around 3.45 volts the current will start tapering off and the voltage will start going up. This will accelerate till the charge is complete. You have...

That cell started with a higher SOC or was a 'weaker' cell. This is normal.

OK. Now it is a matter of being very patient. Set the target voltage on the Power supply before you hook it to the parallel cells and then hook it up and wait. No matter how tempted you are, DO NOT raise the voltage on the power supply.....

Lets do some math. I assume these are new cells. New cells generally come at ~40% SOC. 16 280Ah Cells in parallel will need .6 X 16 X 280 = 2688 Ah to fully charge. At 20A this will take 2688/20=134Hrs to fully charge. Yes, it is normal. Keep in mind that at 3.3V 20 A is only 66W...

I don't have a reference, but have thought about it some. The idea of a very flat profile pack is intriguing to me. If you decide you need cell compression, these layouts could be challenging.

The spec sheet says 10KA interrupt. That is lower than the class C but better than most other types of fuses.

No. The best resolution is to make sure the cells are balanced and the BMS never shuts off.

Nice video. It is true that a breaker will not protect you from direct contact with the hot wire . However, what is not mentioned in the video is that a breaker in conjunction with a neutral-Ground bond will save lives if the short is a ground fault.

I have not run numbers but I suspect his calculator is using the ABYC tables (American Boat and Yacht Council). These tables are much less conservative than the NEC tables. The reason I suspect this is two fold 1) he is an RV builder and a lot of RV builders us the ABYC tables. 2) His...

That sounds correct. To be code complaint it should be outside.

They might exist, but I don't know of any Tigo sells two systems. One is just the rapid shutdown system and the other is an optimizer system that will also do the rapid shutdown. (The Cloud Connect is for the optimizer system that has the cloud internet connect) The rapid shutdown system...

The rapid shutdown requirement has been in the NEC since 2017(?). It is not just CA. I don't know about 'shorting' the panels. I had not heard that before. I guess if the VOC is high enough on the panel it might be needed. Most systems these days use a signal imposed on the power lines...

The max series fuse question is a good one. If we just add the two Iscs together, two strings are still under the 20A. The NEC requires two 1.25 multipliers (That is where the 1.56 comes from). The first 1.25 multiplier is to cover any extra current due to the Isc only representing...

With only two strings, you do not need fuses at all, but you do need an 'accessable' disconnect. (In NEC terms, 'accessible' means 1st responders can get to it.) Fuses or breakers are only needed when there are 3 or more strings. However, you do have to size the wires correctly. The NEC...